A coprolite is a fossilized faeces. It is also known as coprolith. Coprolites are categorized as trace fossils and give evidence about the diet of extinct animals. The term coprolite is derived from the Greek words “kopros” and “lithos” which means dung stone. Coprolites are very rare as the faecal matter decay very rapidly. The indigestible part, bones, scales, teeth, or shells are preserved very well in the coprolites.
In coprolites, the original organic composition is replaced by silicates and calcium carbonates. Sometimes the shape of the coprolites indicates the respective organism. The spiral-shaped coprolites indicate the shark species. The spiral-shaped is due to the presence of the spiral valve in the shark’s intestine.
Coprolites were first identified as “bezoar stones” by British fossil hunter Mary Anning in 1924. Scientists from Australia, New Zealand, and the United States of America reported traces of DNA in the coprolites. They found the coprolites of extinct birds contain ectomycorrhizal fungi (Boast et al., 2018, PNAS).
Qvarnström et al (2021) recently reported an extinct species of beetle Triamyxa coprolithica in a Triassic period coprolite. The age of the fossils is about 230-million-year-old. The beetle belongs to a member of the extinct family Triamyxidae. The coprolite was expected to excrete by Silesaurus opolensis.
References: Boast et al., 2018, PNAS and Qvarnström et al., 2021, Current Biology
The first enzyme discovered was the Diastase. French chemist Jean-François Persoz and Anselme Payen discovered the enzyme Diastase in 1833. Persoz and Payen extracted the enzyme from the malt solution. The name Diastase is derived from the Greek word “diastasis” (separating).
Diastase is a hydrolyzing enzyme that uses water to break the glycosidic bond between two sugar molecules. The enzyme Diastase is also known as the enzyme amylase. Three different types of amylases are α-, β-, or γ-amylase.
The Enzyme Commission number for α-Amylase is EC 184.108.40.206. The enzyme digests the α (1-4)-glycosidic bond between two glucose molecules of glycogen and starch. α-Amylase breaks carbohydrates into dextrins, maltotriose, and maltose. Humans and other mammals produce the enzyme α-Amylase. It is found in the saliva (salivary amylase) and the pancreas (Pancreatic α-amylase). The optimum pH required for enzyme activity is 6.7–7.0.
The Enzyme Commission number for α-Amylase is EC 220.127.116.11. The enzyme digests the second α-1,4 glycosidic bond which resulting into break two glucose units each time. The glucose dimer is called maltose. Bacteria, fungi, and plants produce the enzyme β-amylase. The optimum pH required for enzyme activity is 4.0–5.0. During fruit ripening, the enzyme β-amylase digests the starch into maltose.
The Enzyme Commission number for α-Amylase is EC 18.104.22.168. The enzyme digests of the α-1,6 glycosidic bond of amylose and amylopectin. Digestion of amylose and amylopectin yields glucose. Animals and microbes produce the enzyme γ-amylase. The optimum pH required for enzyme activity is around 3.0.
Cellulose [(C6H10O5)n] is a natural homopolymer and the main structural component of the plant cell wall. Cellulose is the most ubiquitously found organic molecule on earth. Microorganisms, algae, and plants synthesize cellulose fibers from glucose molecules (100s-1000s in numbers). French scientist Anselme Payen discovered the carbohydrate cellulose in 1838 and German Chemist Hermann Staudinger elucidate the chemical structure in 1920.
The glucose molecules are linked together by β(1→4)-glycosidic bonds to forms long cellulose fibers. About 100s to 1000s numbers of glucose molecules are linked together to form a glucose fiber. The enzyme cellulose synthase catalyzes the polymerization of glucose into cellulose fibers.
Cellulose is a water-insoluble polysaccharide. In the plant cells, cellulose is present in the form of fibrils. These fibrils are made up of microfibrils. Cellulose microfibrils consist of long parallel chains of glucose molecules. These polysaccharide chains are joined together by Hydrogen bonds in the microfibrils. These cellulose microfibrils are cementing together by a matrix mainly composed of polysaccharide pectin. This type of arrangement provides stability and high mechanical strength to plant cell walls.
Cellulase is the enzyme that breaks the β(1→4)-glycosidic bonds of cellulose. Due to the absence of cellulase enzyme, humans do not digest cellulose. Termites and herbivores also do not produce cellulase but they can able to digest cellulose due to the presence of gut microbes. The gut bacterium Ruminococcus flavefaciens in the ruminants mammals and the flagellated protists Trichonympha campanula produce cellulase enzyme and digests the cellulose.
Palaemons are decapod crustaceans. They belong to the family Palaemonidae in the Animal Kingdom. They are aquatic animals that live in rivers, lakes, freshwater streams, and ponds. The decapod crustaceans possess 38 appendages (19 pairs). The appendages are external body parts. Out of the 38, 10 appendages are considered legs. The appendages are biramous types and consist of two branches. Each appendage is consists of a base (protopodite) and the inner endopodite and outer exopodite.
The body Palaemon consists of the anterior Cephalothorax (head and thorax) region and the posterior abdomen. The list appendages are as follows:
(1) Appendages in the head region:
(i) Antennules: 1 pair (2 in numbers)
(ii) Antennae: 1 pair (2 in numbers)
(iii) Mandibles: 1 pair (2 in numbers)
(iv) Maxillula: 1 pair (2 in numbers)
(v) Maxillae: 1 pair (2 in numbers)
2) Appendages in the thoracic region:
(i) First maxillipeds: 1 pair (2 in numbers)
(ii) Second Maxillepeds: 1 pair (2 in numbers)
(iii) Third Maxillepeds: 1 pair (2 in numbers)
(iv) Fourth Maxillepeds: 1 pair (2 in numbers)
(V) Fifth Maxillepeds: 1 pair (2 in numbers)
(iv) Walking legs: 3 pairs (10 in numbers)
(3) Abdominal Appendages:
(i) Pleopod: 5 pair (10 in numbers)
(ii) Uropods: 1 pair (2 in numbers)
Baltic prawn (Palaemon adspersus)
Rockpool shrimp (Palaemon elegant)
Giant tiger prawn (Penaeus monodon)
Antibiotics are antimicrobial substances widely used as medications to treat and prevent bacterial and fungal infections. According to their origins, antibiotics can be divided into natural, semi-synthetic, and synthetic. Antibiotics are synthesized bacteria and fungi. These microorganisms synthesized antibiotics as secondary metabolites.
“Penicillin” was discovered by the Scottish physician and microbiologist Sir Alexander Fleming in 1928. He isolated the antibiotic from the green mold Penicillium chrysogenum. The term antibiotic was first time used by Selman Abraham Waksman in 1943.
The Streptomyces group produces more than 65% of medically actively use antibacterial and antifungal antibiotics. The Streptomyces is the largest genus of the phylum Actinobacteria in the Kingdom Bacteria. They are Gram-positive bacteria and can be aquatic or terrestrial.
Below are the lists of antibiotics that are isolated from the group Streptomyces are
- Nystatin is synthesized by Streptomyces noursei and use against the Candida infections of the skin.
- Amphotericin B is synthesized by Streptomyces nodosus and use against the fungal infections mucormycosis and candidiasis.
- Natamycin is synthesized by Streptomyces natalensis and use against the fungal infections of the eye.
- Neomycin is synthesized by Streptomyces fradiae and use to treat tuberculosis caused by Mycobacterium tuberculosis.
- Chloramphenicol is synthesized by Streptomyces venezuelae and use to treat typhoid caused by Salmonella typhi.
- Streptomycin is synthesized by Streptomyces griseus and use to Tuberculosis and Plague caused by Yersinia pestis.
Proteins are biomolecules made up of amino acids. Two amino acids are linked together by an amide-type covalent bond called the peptide bond. The quantitative estimation of protein is an essential step in various biochemical and molecular biology experiments. Ferdinand Rose in 1833 and Polish physiologist G. Piotrowski in 1857 independently discovered a protein estimation assay. The assay shows that in an alkaline solution, a copper (II) ion (Cu2+) forms a pale-purple-colored coordination complex in the presence of peptides. The protein estimation assay is also known as the Piotrowski test.
The protein estimation assay is a colorimetric assay. The intensity of the pale-purple color is directly proportional to the number of peptide bonds between two amino acids. Therefore, the concentration of protein can be measured using the Biuret test. The absorption maxima for the pale-purple-colored coordination complex is 540 nm. The instrument used to measure the absorption is a spectrophotometer. The Beer-Lambert law is used to calculate the concentration of protein.
The Biuret assay requires 1% NaOH or KOH for providing the alkaline environment, aqueous Copper(II) sulfate (CuSO4(H2O)x), and Potassium sodium tartrate. In alkaline conditions, the Cu2+ ion binds with nitrogen atoms present in the peptide bonds of proteins. A pale-purple color formed due to a tri- or tetra-dentate chelation complex between one Cu2+ ion and the four nitrogen atoms of the dipeptides molecules.
Corpora quadrigemina is the brain structure responsible for vision formation in rabbits. The corpora quadrigemina is a part of the midbrain or mesencephalon. The corpora quadrigemina is located on the dorsal surface of the midbrain. The corpora quadrigemina is also known as the quadruplet body or colliculi.
The corpora quadrigemina consists of four elevated structures. They are two superior (rostral) and two inferior colliculi (caudal). Rostral means the anterior part of the head and caudal means the posterior part of the head.
Both the superior and inferior colliculi are composed of grey matter inside and white matter outside. The inferior colliculi involve in processing auditory information. On the other hand, the superior colliculi involve in processing visual information and controlling eye movements.
The superior colliculi is a layered structure consists of the superficial layers or stratum opticum and the deeper layers. Nerve cells of the stratum opticum receive visual information from the retina and process it. Nerves cells of the deeper layers are motor-related neurons and are responsible for eye movements.
The homologous structure involves in vision formation in non-mammalian vertebrates is the optic lobe or optic tectum.
The Hippocampus plays important role in the consolidation of short-term memory into long-term memory. It is located in the temporal lobe of the brain and mainly involves in learning, recognition memory, spatial memory, and navigation.
The Corpus Callosum is a thick nerve fiber present below the cerebral cortex in the brain connecting the right and left cerebral hemispheres. It is only present in placental mammals.
The Corpus Albicans is the degenerated form of the corpus luteum, an endocrine structure found in female ovaries.
The chromosome in a eukaryotic organism is composed of deoxyribonucleic acid (DNA) and proteins (histones and non-histone proteins). The chromosomes are localized in the nucleoplasm inside the nucleus. The nuclear membrane or the nuclear envelop separates the nucleoplasm from the cell cytoplasm. Unlike eukaryotes, where the chromosomes are confined to the nucleus, the chromosome in prokaryotes is found in irregularly shaped regions or undefined nucleus. The nucleus-like structure which contains the naked chromosome is called the nucleoid.
The chromosome in prokaryotic organisms (i.e. bacteria) is only composed of DNA and without histones proteins. The genome of a prokaryote comprises only one chromosome. The chromosome is a double-stranded covalently closed circular DNA. Research on E. coli suggests that the circular chromosomal DNA (~ 4.6 x 106 bp) is associated with Nucleoid-associated proteins or NAPs. Apart from the packaging of the chromosome, NAPs are also involved in the transcription of RNA, replication of DNA, recombination, and repair.
The genophore is referred to as the DNA of a prokaryotic cell or the prokaryotic chromosome. Due to the absence of histones proteins and a true chromatin-like structure, the prokaryotic chromosome is called the genophore. The genophore condensed compacted by a mechanism called supercoiling.
The genophore of the bacterium Mycoplasma genitalium is 580,073 base pairs. The organelle DNA present in mitochondria and chloroplasts are also called genophores.